Siryn (Theresa Cassidy) – This Day In Comics
Like her father, the X-Men’s Banshee, Theresa Maeve Rourke Cassidy is an Irish mutant who possesses a “sonic scream” capable of incapacitating and injuring an opponent’s hearing and sending powerful vibrations through the air. She can use these vibrations to fly. Theresa was raised by Banshee’s cousin and nemesis Black Tom Cassidy without Banshee’s knowledge. By her early teens, she left Black Tom and eventually joined the X-Men offshoots X-Force and later X-Factor. Siryn first appeared in Spider-Woman #37 (December 30, 1980), where she appears as a villain.